The present invention relates generally to biosynthetic processes, and more specifically to organisms having n-propanol and isopropanol, 1,4-butanediol and isopropanol, 1,3-butanediol and isopropanol or methylacrylic and isopropanol biosynthetic capability.
Isopropanol (IPA) is a colorless, flammable liquid that mixes completely with most solvents, including water. The largest use for IPA is as a solvent, including its well known yet small use as “rubbing alcohol,” which is a mixture of IPA and water. As a solvent, IPA is found in many everyday products such as paints, lacquers, thinners, inks, adhesives, general-purpose cleaners, disinfectants, cosmetics, toiletries, de-icers, and pharmaceuticals. Low-grade IPA is also used in motor oils. The second largest use is as a chemical intermediate for the production of isopropylamines, isopropylethers, and isopropyl esters. Isopropanol can potentially be dehydrated to form propylene, a polymer precursor with an annual market of more than 2 million metric tons.
Current global production capacity of isopropanol (IPA) is approximately 6 B lb/yr, with approximately 74% of global IPA capacity concentrated in the US, Europe, and Japan. Isopropanol is manufactured by two petrochemical routes. The predominant process entails the hydration of propylene either with or without sulfuric acid catalysis. Secondarily, IPA is produced via hydrogenation of acetone, which is a by-product formed in the production of phenol and propylene oxide. High-priced propylene is currently driving costs up and margins down throughout the chemical industry motivating the need for an expanded range of low cost feedstocks.
n-Propanol can be potentially used as a gasoline substitute. It is currently used as a multi-purpose solvent in the pharmaceutical industry, for surface coatings and in ink formulations. It is used as a building block for resins and esters, propyl amines and halides. It is also used for packaging and food contact applications. Global production of n-propanol in 2005 was more than 140,000 metric tonnes.
n-Propanol is manufactured by the catalytic hydrogenation of propionaldehyde. Propionaldehyde is itself produced via the oxo process, by hydroformylation of ethylene using carbon monoxide and hydrogen in the presence of a catalyst such as cobalt octacarbonyl or a rhodium complex. It is formed naturally in small amounts in many fermentation processes. For example, microbial production of very small quantities of n-propanol has been detected from certain species of Clostridium via threonine catabolism and from yeast in beer fermentation. No existing microorganism has been reported to produce 1-propanol from sugars in significant amounts.
1,4-Butanediol (14-BDO) is a polymer intermediate and industrial solvent with a global market of about 3 billion lb/year. BDO is currently produced from petrochemical precursors, primarily acetylene, maleic anhydride, and propylene oxide. For example, acetylene is reacted with 2 molecules of formaldehyde in the Reppe synthesis reaction (Kroschwitz and Grant, Encyclopedia of Chem. Tech., John Wiley and Sons, Inc., New York (1999)), followed by catalytic hydrogenation to form 1,4-butanediol. Downstream, 14-BDO can be further transformed; for example, by oxidation to gamma-butyrolactone, which can be further converted to pyrrolidone and N-methyl-pyrrolidone, or hydrogenolysis to tetrahydrofuran. These compounds have varied uses as polymer intermediates, solvents, and additives, and have a combined market of nearly 2 billion lb/year. 1,3-Butanediol (13-BDO) is a four carbon diol commonly used as an organic solvent for food flavoring agents. It is also used as a co-monomer for polyurethane and polyester resins and is widely employed as a hypoglycaemic agent. Optically active 13-BDO is a useful starting material for the synthesis of biologically active compounds and liquid crystals. A substantial commercial use of 1,3-butanediol is subsequent dehydration to afford 1,3-butadiene (Ichikawa, J. Mol. Catalysis. 256:106-112 (2006)), a 25 billion lb/yr petrochemical used to manufacture synthetic rubbers (e.g., tires), latex, and resins. 13-BDO is traditionally produced from acetylene via its hydration. The resulting acetaldehyde is then converted to 3-hydroxybutyraldehdye which is subsequently reduced to form 1,3-BDO. In more recent years, acetylene has been replaced by ethylene as a source of acetaldehyde.
Methylacrylic acid (MAA) is a key precursor of methyl methacrylate (MMA), a chemical intermediate with a global demand in excess of 4.5 billion pounds per year, much of which is converted to polyacrylates. The conventional process for synthesizing methyl methacrylate (i.e., the acetone cyanohydrin route) involves the conversion of hydrogen cyanide (HCN) and acetone to acetone cyanohydrin which then undergoes acid assisted hydrolysis and esterification with methanol to give MAA. Difficulties in handling potentially deadly HCN along with the high costs of byproduct disposal (1.2 tons of ammonium bisulfate are formed per ton of MAA) have sparked a great deal of research aimed at cleaner and more economical processes. As a starting material, MAA can easily be converted into MAA via esterification with methanol. No existing microorganism has been reported to produce MAA from sugars in significant amounts.
Microbial organisms and methods for effectively co-producing commercial quantities of n-propanol and isopropanol, 14-BDO and isopropanol, 13-BDO and isopropanol or MAA and isopropanol are described herein and include related advantages.